Conventionally, linerless labels, which are belt-like label paper sheets, are used for the purpose of saving resources. A linerless label does not use a liner sheet (release liner) that is temporarily attached to an adhesive layer on the back surface side of a label base. Printers for such linerless labels (e.g., thermal printers) have also been developed. JP 3636476B discloses a printer for linerless labels.
FIG. 7 is a schematic side view of a thermal printer 1 as a comparative example. The thermal printer 1 includes a supply unit 3 for supplying a linerless label 2, a detection unit 4, a printing unit 5, and a cutting unit 6.
As apparent from an enlarged cross-sectional view of the linerless label 2 presented in FIG. 7, the linerless label 2 includes a belt-like label base 7, an adhesive layer 8 that is formed on a back surface of the label base 7, and a thermo-sensitive coloring agent layer 9 and a release agent layer 10 that are formed as a lower layer and an upper layer, respectively, on a front surface of the label base 7.
Therefore, when the linerless label 2 is set in a rolled state in the supply unit 3, the adhesive layer 8 and the release agent layer 10 are in contact with each other, and thus the linerless label 2 in the rolled state can be advanced in the form of a belt along a feeding path 11, from the upstream side toward the downstream side, without adhesion between the inner layer and the outer layer of the linerless label 2 in the rolled state. Guide rollers 12, 13 provided along the feeding path 11 can guide the linerless label 2.
Note that position detection marks (not shown) are printed in advance on the back surface of the label base 7 at a predetermined pitch.
The detection unit 4 includes a mark sensor 14, and detects the aforementioned position detection marks on the linerless label 2. In this way, the position of the linerless label 2 relative to the printing unit 5 and the cutting unit 6 can be detected.
The printing unit 5 includes a thermal head 15 and a platen roller 16, supplies and arranges the linerless label 2 to be nipped between the thermal head 15 and the platen roller 16, feeds the linerless label 2 through the rotation and driving of the platen roller 16, and supplies a heating element 15A of the thermal head 15 with printing data. In this way, predetermined printing can be performed on the front surface of the label base 7.
The cutting unit 6 includes a movable blade 17 and a fixed blade 18, and issues individual linerless label strips 2A by cutting off the linerless label 2 at a predetermined pitch. After the cutting unit 6 cuts off the linerless label 2, the linerless label 2 is fed in reverse to be on standby for the next printing. Specifically, a label tip portion 2B stands by while projecting toward the cutting unit 6 from the position of nip between the thermal head 15 and the platen roller 16.
Note that the linerless label 2 may be perforated (not shown) at a predetermined pitch. In this way, individual linerless label strips 2A can be issued by tearing off the printed linerless label 2 at the perforations without using any cutter.
In the thermal printer 1 configured in the above-described manner, components that come into contact with the adhesive layer 8 representing a back surface of the linerless label 2, such as components provided along the feeding path 11 (the guide roller 13, and if necessary, the guide roller 12) and the platen roller 16, are made of materials with releasing properties so as to secure their non-adhesive properties, or have been subjected to surface treatment so that their surfaces have releasing properties (non-adhesive properties). For example, the platen roller 16 is made of silicone rubber.